Cross-Axis Flexural Pivot Joint for Compact Low-Friction Motion
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Solution Overview
Problem
Current surgical instruments face challenges with joint mechanisms that lack flexibility, stability, and a large operating footprint, leading to increased friction, wear, and limited range of motion, especially at smaller sizes.
Innovation Solution
The development of a cross-axis flexural pivot mechanism with elastic deformable flexures that allow for two or more degrees of freedom, reducing friction and increasing the range of motion while maintaining stability and minimizing the overall size of the joint assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If compliant mechanisms with flexible members are used to reduce friction and wear, then the number of parts and friction are reduced, but the mechanisms lack stability and are susceptible to fatigue or failure
Solution Approach 1:
The patent employs a flexible membrane as the core compliant element that provides the desired motion while maintaining structural integrity. The membrane is designed with specific geometry and material properties to achieve large angular ranges of motion without requiring traditional rigid joints, thereby reducing friction and wear while maintaining reliability through careful material selection and structural design
Solution Approach 2:
The patent utilizes large deflection theory and nonlinear elasticity to design the flexible membrane with parameters that allow it to operate in a nonlinear regime. By changing the geometric parameters and material properties of the membrane, the system achieves large ranges of motion while maintaining stability and resistance to fatigue or failure
2Volume of moving object
If the size of surgical instruments is reduced to minimize incisions, then the operating footprint is reduced, but the instruments lack desired flexibility and require larger swept volume inside the patient
Solution Approach 1:
The patent transitions from traditional rigid mechanical joints to a compliant mechanism that achieves motion through elastic deformation in a different dimension. The flexible membrane deforms in multiple directions simultaneously, enabling large angular ranges of motion (up to 85 degrees) within a compact footprint, thus providing high adaptability in a small instrument diameter
Solution Approach 2:
The patent employs dynamic compliant mechanisms where the flexible membrane continuously adapts its shape and stiffness during operation. The mechanism transitions between different deformation states to achieve large ranges of motion, allowing the instrument to maintain flexibility and versatility despite its reduced size
3Ease of operation
If non-compliant revolute joints with pin-in-slot mechanisms are used, then the joint allows rotation between tool portions, but the mechanism produces undesirable friction, wear, and motion
Solution Approach 1:
The patent replaces traditional mechanical pin-in-slot revolute joints with a compliant mechanism based on elastic deformation. Instead of using rigid components with physical contact that generate friction and wear, the system uses a flexible membrane that deforms elastically to achieve the same rotational capability, thereby eliminating the harmful effects of mechanical contact
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cross-axis flexural pivot mechanism enables a larger range of motion (up to 85 degrees) and reduces the size of the joint assembly, minimizing friction and wear, while maintaining stability and flexibility, making it suitable for small-scale surgical instruments.
Implementation Method 1
The flexure is configured to deform elastically when the first joint member and the second joint member move from a first configuration to a second configuration
Data Source
AI summary
The embodiments described herein can be used in a variety of grasping, cutting, and manipulating operations. In some embodiments, an apparatus includes a first joint member, a second joint member, and a flexure. The first joint member includes a first connection portion and a contact surface. The second joint member including a second connection portion. A first end portion of the flexure is coupled to the first connection portion, and a second end portion of the flexure is coupled to the second connection portion. The flexure is configured to deform elastically when the first joint member and the second joint member move from a first configuration to a second configuration. When in the first configuration, the central portion of the flexure is spaced apart from the contact portion. When in the second configuration, the central portion of the flexure contacting the contact portion.